As computer accessing of large quantities of information increases, the ability of users to navigate large information spaces and to maintain visualization or personal perspectives thereof decreases [1] (bracketed numbers reference publications identified in Appendix A).
The need for this type of control has been expressed most recently by Furnas [2], Mills [3], Degen [4], and Chimera [5].
Furnas' solution to the problem of understanding the limited information available in a window of large information structures is to provide in the window the detailed region to be considered in the context of important preceding or succeeding parts of the large structure. For example, to edit lines in the middle of a program, the window would also display, say, declarations at the beginning of the program. No magnification of desired information or shrinkage of undesired information is employed; rather, the desired program information is normally displayed, and many parts of the program are omitted from the display.
Mills et al addressed the issue of giving users access to video data by magnifying time through successive hierarchial extraction of increasingly detailed segments. Each expanded view was displayed in a separate window of the display. And each segment view, as well as the total video view, including the time lines associated therewith, were linearly arranged from a temporal standpoint.
Degen et al moved marks on audio tape to a digitized counterpart document scroll bar, and let the user change the visual scaling of time within a single window, as well as the speed of playback. But, again, the visual representations, whether of the original size or of the zoomed expanded size, had a linear temporal structure.
Chimera, on the other hand, maintained a full display within the window but was unable to provide a zooming feature or expanded segment view of a text listing. Instead, Chimera used scroll bars that, independent of the original data's representation, indicate relative values of list attributes by respectively scaling proportions of list item indicators, according to those attributes, in the scroll bars.
Furnas shows in a single window multiple fisheye views of document segments. But Purnas doesn't disclose how a user can select which segments to display, or the means to magnify certain segments, or the means to control the degree of magnification, nor does Furnas provided a scroll bar or its equivalent as a convenient interface for the user to manipulate the display.